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Alcohol might help you nod off, but even just a couple of drinks can affect the quality of your sleep. And if you're regularly drinking more than the government's lower risk guidelines, you may find you wake up the next day feeling like you haven't had any rest at all.

How alcohol affects your sleep patterns

Even a couple of drinks can interfere with the normal sleep process. When you drink alcohol close to bedtime, you can go straight into deep sleep, missing out on the usual first stage of sleep, called rapid eye movement (REM) sleep.

"Deep sleep is when the body restores itself, and alcohol can interfere with this," explains Dr John Shneerson, head of the sleep centre at Papworth Hospital in Cambridge. "As the alcohol starts to wear off, your body can come out of deep sleep and back into REM sleep, which is much easier to wake from. That's why you often wake up after just a few hours sleep when you've been drinking."

In the course of a night you usually have six to seven cycles of REM sleep, which leaves you feeling refreshed. However, if you've been drinking you'll typically have only one to two, meaning you can wake feeling exhausted.

Drinking can equal a disturbed night’s sleep

When you drink more than usual, you may have to get up in the night to go to the toilet. And it's not just the liquid you've drunk that you'll be getting rid of. Alcohol is a diuretic, which means it encourages the body to lose extra fluid though sweat too, making you dehydrated.

Drinking can also make you snore loudly. It relaxes the muscles in your body, which means the tissue in your throat, mouth and nose can stop air flowing smoothly, and is more likely to vibrate.

So, all in all alcohol can equal a fitful night's sleep.

Why you should avoid alcohol just before bedtime

If you are drinking alcohol, try to avoid it too close to bedtime. Give your body time to process the alcohol you've drunk before you try to sleep – on average it takes an hour to process one unit, but this can vary widely from person to person.

Our unit calculator will tell you how many units are in your favourite drinks. Sign up to MyDrinkaware to keep track of what you're drinking over time and set yourself goals for cutting back.